Rebuilt rechargeable battery and method

ABSTRACT

A rechargeable power tool battery is rebuilt by replacing its spent cells with an array of replacement cells in which connections are made by conductive connectors, ends of which are clamped by bent-over arms of star-shaped malleable metal grips, the hubs of which are spot welded to cell terminals by the replacement cell supplier. Replacement cells can be supplied in pairs with the positive terminal of one cell of the pair permanently connected to the negative terminal of the other cell of the pair and with the other positive and negative terminals each provided with a spot-welded star-shaped grip.

FIELD OF THE INVENTION

This invention relates to batteries, and more particularly to therebuilding of rechargeable batteries of the kind used in power toolssuch cordless drills, saws, vacuum cleaner and the like, as well as incordless lighting devices, radio-controlled model automobiles, andnumerous other devices.

BACKGROUND OF THE INVENTION

A rechargeable battery typically has a useful life between approximatelythree hundred and one thousand charging cycles. Eventually, due tochemical changes in the electrochemical cells making up the battery,they no longer hold their charge, and require replacement.

Conventionally, when a rechargeable battery reaches the end of its life,the user purchases a new one, or sends the spent battery to a rebuilder,who will install new cells and spot-weld connectors to them usingindustry-specific welding equipment. Both conventional solutions arecostly, and the latter solution, professional rebuilding, is alsotime-consuming, and puts the cordless tool out of service for the timerequired for rebuilding, unless the user maintains a spare battery.

There are numerous different kinds of rechargeable batteries forcordless tools, and these batteries having varying numbers of cells anda variety of different cell arrangements. Because of the variety ofbatteries, it is impractical for anyone to supply replacement kitsconsisting of replacement cells with their electrical interconnectionsalready made.

A user can obtain individual replacement cells, but the expensivespecialized welding equipment needed for battery rebuilding is beyondthe means of most ordinary users. On the other hand, an attempt tosolder connections to the replacement cells, will often overheat thereplacement cells and ruin them. In the case of attempts to solderconnections to lithium ion (Li ion) cells, there is a significant riskof explosion and personal injury.

SUMMARY OF THE INVENTION

This invention addresses the above-described problems by means of aninexpensive kit containing a plurality of new rechargeable cells, whichcan be assembled in any of a wide variety of cell configurations. Thekit also includes connectors which can be used to interconnect the cellsand to connect the array of cells to output terminals without the needfor welding or soldering. Using the kit, a user can produce areplacement battery by removing the spent cells from the battery case,assembling replacement cells in the same configuration as that of thespent cells, making electrical interconnections, placing theinterconnected cells into the battery case, and making final connectionsto the battery terminals. These steps can be carried out easily andwithout the need for special skills.

In a preferred embodiment, a key to the solution to the problem ofmaking interconnections in the array of cells is the use of“star”-shaped metal grips welded to cell terminals, and conductiveconnectors having enlarged ends which can be clamped to the star-shapedgrips by bending radial arms of the stars over the connector ends. Eachof the conductive connectors is preferably a unitary strip of sheetmetal.

To rebuild most batteries in which the cells are connected in series, itis possible to supply cells in pairs, each pair consisting of twoside-by-side, oppositely oriented, cells with a positive terminal of onecell of the pair already connected to a negative terminal of anothercell of the pair, and with star grips welded to the other two terminals.

In some battery packs that include an array of cylindrical cells inside-by-side relationship, one or more connections will be made at thetop of an array, and one or more connections will be made at the bottomof the array. In some cases, these connections will be made directly tobattery pack terminals. In others, a connection will be made from thetop or bottom of a cell in the side-by-side array to one or moreadditional cells disposed in a “crown,” i.e., a part of the battery packthat extends upward from the part in which the side-by-side array isenclosed. The crown is typically designed to fit removably into asimilarly shaped receptacle of a power tool, and includes the batteryterminals through which current is delivered to the tool.

To enable rebuilding of battery packs having side-by-side arrays ofcells, in which connections must be made both to the top and to thebottom of the side-by-side array, a replacement kit may include not onlypre-connected pairs of cells, but one or more individual cells havingstar-shaped grips at both ends. Preferably, a replacement kit shouldinclude three such individual cells.

Some rechargeable batteries, such as those using lithium ion (Li ion)cells are composed of series connected units, each unit being composedof two cells electrically connected in parallel. In such a case, stargrips can be used as in the above-mentioned series-connected battery,but are interconnected by metal connectors each having four stargrip-engaging parts.

The rebuilt rechargeable battery in accordance with the inventioncomprising a battery case and a plurality of electrochemical cellswithin the battery case. The cells are of substantially uniform size,each having a cylindrical shell, a positive terminal at one end of theshell, and a negative terminal at an opposite end of the shell. Thecells are arranged in an array in which the cylindrical shell of eachcell is in close proximity to the cylindrical shell of at least oneother cell in the array, and in which a first set of ends composed ofone end of each of the shells is disposed substantially in a first planeand the remaining ends of the shells are disposed substantially in asecond plane parallel to the first plane and spaced from the first planeby a distance substantially equal to the length of each of the shells.

The cells are interconnected electrically by a plurality of electricalconnections, each being from a terminal of one cell to a terminal ofanother cell. Each connection comprises first and second star-shapedgrips. Each grip is composed of sheet metal and has a hub and aplurality of arms extending from the hub. The hub of the first grip iswelded to a terminal of one cell, and the hub of the second grip iswelded to a terminal of another cell. A conductive connector connectingthe first and second grips has a first part engaged with the hub of thefirst grip and a second part engaged with the hub of the second grip.The arms of each grip initially extend radially outward from the hub.When the conductive connector is in place, with its first and secondparts in engagement with the hubs, a plurality of arms of the first gripis bent over the first part of the connector, clamping the first partagainst the hub of the first grip, and a plurality of arms of the secondgrip is bent over the second part, clamping the second part against thehub of the second grip.

In embodiments in which the conductive connector only connects aterminal of one cell to a terminal of another cell, the connectorpreferably includes an elongated intermediate part connecting its firstand second parts thereof, and the intermediate part is narrower thaneach of the first and second parts in a direction parallel to the planesin which the ends of the shells are disposed and perpendicular to itsdirection of elongation. Although the connector can consist of twodisc-shaped parts connected by a wire, as mentioned previously, thepreferred connector is a dumbbell-shaped unitary strip composed of twodisc-shaped end parts connected by a narrow connecting part.

In a preferred embodiment, in which each of the first and second partsof the conductive connector is circular in shape, each of the first andsecond parts has a diameter larger than the diameter of the grip hubagainst which it is clamped.

To prevent the circular part of a conductive connector from sliding outof the star-shaped grip with which it is engaged, the bends of at leastthree arms of the grip bent over the circular part contact the peripheryof the circular part at corners of a triangle within which the center ofthe circular part is located.

In the case of a battery composed of series-connected cells, the cellscan be supplied in a rebuilding kit in pairs of side-by-side cells, withterminals at one end of the pair of cells directly welded to aconductive connector. One or more solitary additional cells havingstar-shaped connectors at both ends may also be provided in therebuilding kit. The pairs of cells can be assembled into the desiredarray with the direct welded connections in a plane in which one end ofeach cell is situated. Connections can then be made from one star-shapedgrip to another in a plane in which the other ends of the cells aresituated. The solitary cells allow for connections to the bottom of thearray where needed to duplicate the original battery connections.

The star-shaped arms allow connections from one grip to another in anyconfiguration of the cell array. Since one cylindrical cell can besurrounded by six more similar cylindrical cells, all touching the onecell, it is possible to utilize star-shaped grips having six armsuniformly spaced around the hub, and to bend five of the arms over adisc-shaped end of a conductive connector and to position theintermediate portion, i.e., the bridge portion, of the connector overthe remaining unbent arm of the grip. In such an arrangement, theintermediate portion of the connector can be made to extend to anyadjacent cell by leaving only one arm of the grip unbent.

Although each of the star-shaped grips can have as few as three arms, itis preferred that each star-shaped grip have at least five arms, andstill more preferable that each star-shaped grip have eight arms. Whenone or more of the arms is not bent over a hub-engaging part of theconnecting strip, space is allowed for the intermediate part of theconnecting strip to extend from the grip to another grip, overlying thearm or arms that are not bent over the hub-engaging part of theconnecting strip.

The arms of the star-shaped grips can have any of various shapes. Forexample, each arms can be in the form of an elongated rectangle.Preferably, however, each arm is triangular in shape.

Another aspect of the invention is a method for rebuilding arechargeable battery. A battery which can be rebuilt by the methodcomprises a set of spent, electrically interconnected, electrochemicalcells of substantially uniform size within a battery case. The cells areconnected either directly, or through one or more additional cells, tobattery terminals on the battery case. Each of the cells has acylindrical shell, a positive terminal at one end of the shell, and anegative terminal at an opposite end of the shell. The cells of the setare arranged in an array in which the cylindrical shell of each cell isin close proximity to the cylindrical shell of at least one other cellin the array, and a first set of ends composed of one end of each of theshells is disposed substantially in a first plane and the remaining endsof the shells are disposed substantially in a second plane parallel tothe first plane and spaced from the first plane by a distancesubstantially equal to the length of each of the shells.

The method comprising a set of steps, which can be, but are notnecessarily, carried out in the following sequence. The first step isthe removal of the spent cells from the battery case. A fresh set ofcells is then arranged in substantially the same arrangement as that ofthe spent cells. Metal grips are permanently connected, preferablyfactory-welded, to terminals of the fresh set of cells, so the cells aresupplied to the rebuilder with grips already welded to them. Electricalinterconnections, corresponding to the electrical interconnections inthe set of spent cells, are established in the fresh set of cells. Theseelectrical interconnections are established at least in part byconnecting grips to one another by mechanically securing first andsecond parts of a conductive connector to the grips to be connected.Insulating paper, referred to as “fish paper,” may be cut to size andpositioned against the top and bottom planes of the cells to preventshort circuiting caused by contact of the cell terminals or theirconnectors with wires or metal objects within the battery case. Theinterconnected fresh set of cells is then enclosed in the battery case,and electrical connections are made from the fresh set of cells, eitherdirectly, or through additional cells apart form the array, to thebattery terminals on the battery case.

Preferably, the grips are star-shaped grips having hubs, and the gripsare secured to the conductive connectors by positioning first and secondparts of the connectors in contact with hubs of grips to be connected,and bending arms of the grips over the first and second parts of theconnector, thereby clamping the first and second parts of the connectorto the hubs of the grips.

Rebuilding a rechargeable battery in accordance with the invention has anumber of advantages. Rebuilding can be carried out quickly andinexpensively by the user without the risk of damage to replacementcells by heat. The star-shaped grips produce reliable interconnections.The same rebuilding kit can be used to rebuild a wide variety ofbatteries. In addition, the rebuilding kit is environmentallyadvantageous in that it allows for reuse of the battery case so that thebattery case does not need to be thrown away, and in that the separationof the spent cells from the battery case in the rebuilding processencourages recycling of spent cells. Further objects and advantages ofthe invention will be apparent from the following description when readin conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a star-shaped grip in accordance with theinvention;

FIG. 2 is a plan view of a conductive connector having enlarged,circular, grip hub-engaging ends connected by a narrow intermediatepart;

FIG. 3 is a perspective view of a single replacement cell showing astar-shaped grip spot-welded to its upper terminal;

FIG. 4 is another perspective view of the single replacement cell ofFIG. 3, showing the star-shaped grip spot-welded to its lower terminal;

FIG. 5 is a perspective view of a permanently connected cell pair havingstar-shaped grips welded to the upper terminals of the cells;

FIG. 6 is a perspective view of the cell pair of FIG. 5 showing thepermanent connection between the lower terminals;

FIG. 7 is a top plan view of an array of replacement cells in which theterminals on the top of the array are interconnected by star-shapedgrips and connecting strips;

FIG. 8 is a bottom plan view of the array of replacement cells in FIG.7, showing permanent welded interconnections between the cells of cellpairs at the bottom of the array;

FIG. 9 is a top plan view of another array of replacement cells in whichthe terminals on the top of the array are interconnected by star-shapedgrips and connecting strips;

FIG. 10 is a bottom plan view of the array of replacement cells in FIG.9, showing permanent welded interconnections between the cells of cellpairs at the bottom of the array;

FIG. 11 is a top plan view of still another array composed of an oddnumber of replacement cells, in which terminals on the top of the arrayare interconnected by star-shaped grips and connecting strips and inwhich a terminal of one cell has a star-shaped grip connected to a discat the end of a connecting wire;

FIG. 12 is a bottom plan view of the array of replacement cells in FIG.11, showing permanent welded interconnections between the cells of cellpairs at the bottom of the array, and in which a terminal of one cell,which is not part of a permanently connected pair, has a star-shapedgrip connected to a disc at the end of a connecting wire;

FIG. 13 is a top plan view of still another array composed of an oddnumber of replacement cells;

FIG. 14 is a bottom plan view of the array of replacement cells in FIG.13;

FIG. 15 is a top plan view of still another array composed of an oddnumber of replacement cells, in which terminals on the top of the arrayare interconnected by star-shaped grips and connecting strips, and inwhich a terminal at one end of one of the cells is connected by a wireto a terminal at the opposite end of an adjacent cell.

FIG. 16 is a bottom plan view of the array of replacement cells in FIG.15, showing permanent welded interconnections between the cells of cellpairs at the bottom of the array, and also showing the wire connection;

FIG. 17 is a top plan view of still another array of replacement cellsin which terminals on the top of the array are interconnected bystar-shaped grips and connecting strips;

FIG. 18 is a bottom plan view of the array of replacement cells in FIG.17, showing permanent welded interconnections between the cells of cellpairs at the bottom of the array;

FIG. 19 is a top plan view of still another array of replacement cellsin which terminals on the top of the array are interconnected bystar-shaped grips and connecting strips, and in which a terminal of oneof he cells is connected to a battery terminal by a wire;

FIG. 20 is a bottom plan view of the array of replacement cells in FIG.19, showing permanent welded interconnections between the cells of cellpairs at the bottom of the array and in which a bottom terminal of oneof the cells is connected to a battery terminal by a wire;

FIG. 21 is a top plan view of an array of cells in which pairs of cellsare connected in sets of two parallel cells, and the sets are connectedin series, in which the parallel and series connections are made usingstar-shaped grips and connecting strips which differ from the connectingstrips used in the embodiments shown in FIGS. 7-20; and

FIG. 22 is a bottom plan view of the array of cells shown in FIG. 21,showing the use of star-shaped grips and connecting strips to makeparallel and series connections.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The star-shaped grip 30 of FIG. 1 comprises a hub 32 and a set of eighttriangular arms 34-48 extending radially from the hub and disposeduniformly around the perimeter of the hub. The outer ends of the armsare pointed, and the inner ends of the arms meet at eight pointsuniformly spaced at 45 degree intervals on the perimeter of an imaginarycircle defining the hub diameter. The hub diameter is preferably lessthan the diameter of a replacement cell, which is usually 2.2 cm. Thediameter of a circle circumscribing the star with its arms extended canbe greater than the cell diameter. The grip can be composed of any ofvarious metals, but should exhibit good electrical conductivity,malleability, and resistance to corrosion. Nickel and various nickelalloys are examples of suitable materials.

The conductive connector 50 in FIG. 2, which can also be composed ofnickel, a nickel alloy, or another suitable metal, is a sheet metalstrip comprising an two circular parts 52 and 54 at opposite ends of annarrower intermediate part, or bridge, 56. The circular parts of theconnecting strip can be held by bent-over arms of star-shaped elementson two adjacent cells, as shown in FIG. 7. The diameter of each of thecircular parts 52 and 54 of the connecting strip is comparable to thediameter of the hub 32 of the star-shaped grip 30. Preferably, thediameter of the circular parts 52 and 54 of the connecting stripapproximately equal to, or slightly greater than, the diameter of thehub 32, so that the arms of a star-shaped grip can embrace the edges ofthe circular part when they are bent around it. The distance from thecenter of part 52 to the center of part 54 is preferably approximatelyequal to the diameter of a replacement cell so that the parts 52 and 54can be centered on the star-shaped elements of two adjacent, mutuallycontacting, cells.

As shown in FIGS. 3 and 4, a solitary cylindrical replacement cell 58has a star-shaped grip 60 connected to a terminal at one end and anotherstar-shaped grip 62 connected to a terminal at its opposite end. Thestar shaped grips are connected to the terminals by spot welding thehubs to the terminals. Spot welding the grips to the cells is carriedout at a factory, using industry-specific spot welding equipment. Thecells will be supplied to the consumer in rebuilding kits with thestar-shaped grips pre-welded to the cells.

Replacement cell 58 can be disposed along with a number of similarcylindrical replacement cells in an array in which the cells are inside-by-side relationship with one another, and with their terminals intwo parallel planes spaced from each other by the length of a cell. Eachcell in the array has at least one oppositely oriented cell adjacent toit. In that array, the cells can be electrically connected in series byconnecting positive terminals to negative terminals in both planes.

For most series-connected replacement cell arrays it is possible toutilize pairs of cells in which the positive terminal of one cell of thepair is permanently connected to the negative terminal of the other cellby directly welding a conductive connector to those terminals. FIGS. 5and 6 illustrate such a pair of cells 64 and 66, in which the positiveterminal 68 of cell 64 is directly connected to the negative terminal 70of cell 66 by a conductive connector 72, spot-welded to terminals 68 and70. A star-shaped grip 74 is spot-welded to the negative terminal ofcell 64, and star-shaped grip 76 is spot-welded to the positive terminalof cell 66. A replacement battery can include a plurality of similarpairs of cells in which the interconnections composed of star-shapedgrips and conductive connectors are all on one side, e.g., the top, ofthe array.

FIGS. 7 and 8 illustrate an array composed of a plurality of pairs ofcells in which terminals of the cells of each pair are permanentlyconnected by a strip as shown in FIG. 6. In this array, ten 1.2 voltNiCd (nickel-cadmium) cells are connected in series to form a 12 voltpower tool battery. The interconnections in the top plane are made bystar-shaped grips and strip connectors, e.g., star grips 78 and 80 andstrip connector 82. One end of wire 84 is suitably pre-connected, forexample by soldering or crimping, to a disc 86. The disc is secured to astar grip welded to the positive terminal of cell 88. The other end ofwire 84 is connected to a positive battery terminal 90. A similarconnection is made from the negative terminal of cell 92 to a negativebattery terminal 94.

As shown in FIG. 8, the connections in the bottom plane are permanentconnections made by welding metal connecting strips, e.g., strip 96,directly to cell terminals. The pairs of cells are provided to theconsumer with their permanent connections already made in a factory,using industry-specific spot-welding equipment.

Pairs of cells as shown in FIGS. 5 and 6 can be arranged in any of avariety of arrays, examples of which are depicted in FIGS. 9-20.

In FIGS. 9 and 10, array 98 is composed of fourteen series-connectedcells, which can be connected by leads 99 to a crown containing stillanother cell (not shown), to form an 18 volt battery pack. In this case,both leads are connected to terminals on the top of the side-by-sidearray.

In FIGS. 11 and 12, array 100 is composed of nine series-connectedcells. A terminal at one end of the series, on the top of the array, isconnected to one of leads 101, and the terminal at the other end of theseries is connected at the bottom of the array to another lead 101. Thetwo leads 101 are connected to a crown containing still another cell(not shown) to provide a 12 volt battery pack. Array 100 is composed offour pre-connected pairs of cells, and one additional cell 58 havingstar-shaped connectors at both ends.

FIGS. 13 and 14 show an array 102 composed of fifteen series-connectedcells. A terminal at one end of the series, on the top of the array, isconnected to one of leads 103, and the terminal at the other end of theseries is connected at the bottom of the array to another lead 103. Thetwo leads 103 are connected to a crown containing still another cell(not shown) to provide a 19.2 volt battery pack. Array 102 is composedof seven pre-connected pairs of cells, and one additional cell 58 havingstar-shaped connectors at both ends.

FIGS. 15 and 16 show an array 104 composed of fifteen series-connectedcells, the terminals at opposite ends of the series are both on the topside of the array and are connected by leads 105 to positive andnegative battery terminals. The array is composed of seven pre-connectedpairs of cells and one solitary cell 106 having star-shaped grips atboth ends. A lead 107 at the bottom side terminal of cell 106 isconnected to a top side terminal of cell 108, which is one of apre-connected pair. This battery pack, which consists of a total offifteen cells, delivers 18 volts.

FIGS. 17 and 18 show another array 110 composed of seven pre-connectedpairs of cells connected electrically in series. Leads 112, which areboth connected to star-shaped grips on the top side of the array, areconnected to a crown (not shown) having still another cell, in order toproduce an 18 volt battery pack.

FIGS. 19 and 20 show still another series-connected array composed ofseven pre-connected pairs of cells and one solitary cell 116 havingstar-shaped grips at both of its ends. The positive terminal of cell 116is at one end of the series. A lead 118 is connected from the positiveterminal of cell 116 to a positive battery terminal and a lead 120 isconnected from the negative terminal of a cell 122 at the opposite endof the series to a negative battery terminal.

The examples in FIGS. 7-20 represent replacement cell arrays forrepresentative rechargeable NiCd power tool batteries currently beingsold. In each case, individual NiCd cells are connected in series from apositive battery terminal to a negative battery terminal.

There are also cases in which a rechargeable battery incorporates aseries-parallel arrangement, e.g., an arrangement in which units, eachconsisting of two cells in parallel, are connected in series. FIGS. 21and 22 illustrate an example of such a rechargeable battery. In thiscase, the battery is an 18 volt battery composed of ten 3.6 volt lithiumion (Li ion) cells in parallel-connected pairs. Here, star-shaped gripsare provided on both ends of each of the ten cells.

On the top side of the array of cells, as shown in FIG. 21, a connectionto a positive battery terminal (not shown) is made through a metal strip124, which can be the same metal conductor used to connect the originalbattery to the positive terminal, or a part of the original metalconductor. The strip 124 is clamped by first and second pairs of ears126 and 128, which extend from side edges of a connecting strip 130, andare bent over strip 124. The connecting strip 130 comprises two discswhich are clamped to positive terminals of cells 132 and 136 by a starshaped grips 134 and 138 similar to the star-shaped grips in thepreviously described embodiments. The ears 126 extend from the sideedges of a part of the connecting strip which connects one disc to theother. Ears 128 extend from side edges of an extension 139 of theconnecting strip.

On the bottom side of the array, as shown in FIG. 22, the negativeterminals of cells 132 and 136 are connected together by a metal strip140, which has four circular parts 142, 144, 146 and 148, connectedrespectively to the negative terminals of cells 136 and 132, and thepositive terminals of cells 150 and 152. Each of the four circular partsof strip 126 is held by a star-shape grip, e.g., grip 154.

Ears 153 on a central part of strip 140, and ears 155 on an extension ofstrip 140, are bent over a metal strip 157 from the original battery.This metal strip can be used to tap a voltage less than the full 18volts of which the battery is capable, for operation of controlelectronics or for switching a lower voltage to a load.

As shown in FIG. 21, the negative terminals of cells 150 and 152 areconnected to the positive terminals of cells 154 and 156 by a similarfour-cornered metal strip 158. Similar metals strips, each having fourcircular parts engageable by star-shaped grips, connect the cells inseries/parallel relationship, and from one or more of the four-corneredstrips, strips similar to strip 157 can be used to tap intermediatevoltages. Intermediate voltages can also be tapped using discs connectedto wires as in FIG. 7. If no intermediate voltages are required, thetapping connections can of course be eliminated.

At the negative end of the battery, the negative battery terminal (notshown) is connected to the negative terminals of cells 164 and 166 by astrip 160, which is clamped by two sets of ears on a connector 162.

The battery thus comprises five pairs of parallel-connected cells, thepairs being connected in series between a positive battery terminalconnecting strip 124 and a negative battery terminal connecting strip160.

The star-shaped grips can thus be used not only to connect cells inseries as in the examples illustrated in FIGS. 7-20, but also to connectcells in a series/parallel arrangement as shown in FIGS. 21 and 22.

The preferred star-shaped grips have eight arms spaced uniformly aboutthe periphery of their hubs. Such grips can be used in both in theseries-connected embodiments of FIGS. 7-20 and inseries/parallel-connected embodiments such as the one shown in FIGS. 21and 22. For grips to be used only in the series-connected embodiments,the number of arms can be relatively small. A connecting strip attachedto a six-armed grip can extend from the grip in any one of sixdirections sixty degrees apart from one another, by positioning theconnecting strip so that it overlies one selected arm that is not bentover the part of the connecting strip held by the other arms. The sameis true of a grip having from three to five arms. A grip having at leastfive arms is preferred as it provides a large area of contact with theconnecting strip even if one of the arms is unbent, it allows for arelatively wide bridge, and it allows the bridge to be oriented at anydesired angle from the cell terminal with only one arm of the gripunbent. The eight-armed grip of the preferred embodiment exhibitssimilar advantages.

A rebuilding kit according to the invention can include a set ofreplacement cells, either as individual cells with grips at both ends asin FIGS. 3 and 4, or as permanently connected pairs of cells as in FIGS.5 and 6, preferably along with one or more solitary replacement cells,each having a star-shaped grip attached to both ends. The kit will alsoinclude connecting strips as in FIG. 2, and discs with leads soldered tothem as in FIG. 7 for making connections to the battery terminals on thebattery case. The rebuilding kit can include any of various kinds ofrechargeable cells, including, but not limited to, NiMH (nickel—metalhydride) cells, Li ion (lithium ion) cells and NiCd (nickel-cadmium)cells. Fish paper for protection of the battery from short-circuitingmay also be included.

Although star-shaped grips are preferred for most applications, inapplications where sufficient space is available, many of the advantagesof the invention can be realized in alternative embodiments in whichgrips welded to terminals of replacement cells and the connectors theextend from a grip on one cell to a grip on another cell utilize snapconnectors of the kind described in U.S. Pat. No. 4,024,953 granted May24, 1977. The disclosure of U.S. Pat. No. 4,024,953 is incorporated byreference.

1. A rebuilt rechargeable battery comprising: a battery case; aplurality of electrochemical cells within said battery case, each ofsaid cells having a cylindrical shell, a positive terminal at one end ofthe shell, and a negative terminal at an opposite end of the shell,wherein at least two of said cells are electrically connected in serieswith each other by an electrical connection comprising first and secondstar-shaped grips and a conductive connector; in which each grip iscomposed of sheet metal and has a hub and a plurality of arms extendingfrom the hub; in which the hub of the first grip is welded to thepositive terminal of one of said two cells, and the hub of the secondgrip is welded to the negative terminal of the other of said two cells;in which said conductive connector has a first part engaged with the hubof the first grip and a second part engaged with the hub of the secondgrip; in which a plurality of arms of the first grip is bent over thefirst part of the conductive connector whereby said first part isclamped the bent arms of the first grip against the hub of the firstgrip, and a plurality of arms of the second grip is bent over the secondpart of the conductive connector whereby said second part is clamped bythe bent arms of the second grip against the hub of the second grip. 2.A rebuilt rechargeable battery according to claim 1, in which saidconductive connector is a unitary strip of sheet metal.
 3. A rebuiltrechargeable battery according to claim 1, in which each said conductiveconnector includes an elongated intermediate part connecting said firstand second parts thereof, and in which said intermediate part isnarrower than each of said first and second parts.
 4. A rebuiltrechargeable battery according to claim 1, in which each of said firstand second parts of the conductive connector is circular in shape.
 5. Arebuilt rechargeable battery according to claim 1, in which each of saidfirst and second parts of the conductive connector is circular in shapeand has a diameter larger than the diameter of the grip hub againstwhich it is clamped.
 6. A rebuilt rechargeable battery according toclaim 1, in which each of said first and second parts of the conductiveconnector is circular in shape, the bends of at least three arms of thestar-shaped grip bent over the first part contact the periphery of thefirst part at corners of a triangle within which the center of saidfirst part is located, and the bends of at least three arms of thestar-shaped grip contact the periphery of the second part at corners ofa triangle within which the center of said second part is located.
 7. Arebuilt rechargeable battery according to claim 1, in which said cellsconsist of pairs of cells, in which the cells of each pair are inside-by-side relationship whereby each pair has terminals at a first endand terminals at a second end, and in which terminals at one end of eachpair are directly welded to a conductive connector.
 8. A rebuiltrechargeable battery according to claim 1, in which each of saidstar-shaped grips has at least five arms uniformly spaced around the hubthereof, and in which each said conductive connector includes anintermediate part connecting said first and second parts thereof andoverlying at least one arm of each of the star-shaped grips to which theconductive connector is connected.
 9. A rebuilt rechargeable batterycomprising: a battery case; a plurality of electrochemical cells ofsubstantially uniform size within said battery case, each of said cellshaving a cylindrical shell, a positive terminal at one end of the shell,and a negative terminal at an opposite end of the shell, and said cellsbeing arranged in an array in which the cylindrical shell of each cellis in close proximity to the cylindrical shell of at least one othercell in the array, and in which a first set of ends composed of one endof each of the shells is disposed substantially in a first plane and theremaining ends of the shells are disposed substantially in a secondplane parallel to the first plane and spaced from the first plane by adistance substantially equal to the length of each of the shells; and aplurality of electrical connections, each connection being from aterminal of one cell to a terminal of another cell and comprising firstand second star-shaped grips, each composed of sheet metal and having ahub and a plurality of arms extending from the hub, the hub of the firstgrip being welded to said terminal of one cell, and the hub of thesecond grip being welded to said terminal of another cell, and aconductive connector connecting said first and second grips, theconductive connector having a first part engaged with the hub of thefirst grip and a second part engaged with the hub of the second grip;wherein a plurality of arms of the first grip is bent over the firstpart of the conductive connector whereby said first part is clamped thebent arms of the first grip against the hub of the first grip, and aplurality of arms of the second grip is bent over the second part of theconductive connector whereby said second part is clamped by the bentarms of the second grip against the hub of the second grip.
 10. Arebuilt rechargeable battery according to claim 8, in which each saidconductive connector is a unitary strip of sheet metal.
 11. A rebuiltrechargeable battery according to claim 8, in which each said conductiveconnector includes an elongated intermediate part connecting said firstand second parts thereof, and in which said intermediate part isnarrower than each of said first and second parts in a directionparallel to said planes and perpendicular to its direction ofelongation.
 12. A rebuilt rechargeable battery according to claim 8, inwhich each of said first and second parts of each said conductiveconnector is circular in shape.
 13. A rebuilt rechargeable batteryaccording to claim 8, in which each of said first and second parts ofeach conductive connector is circular in shape and has a diameter largerthan the diameter of the grip hub against which it is clamped.
 14. Arebuilt rechargeable battery according to claim 8, in which each of saidfirst and second parts of each conductive connector is circular inshape, the bends of at least three arms of the star-shaped grip bentover the first part contact the periphery of the first part at cornersof a triangle within which the center of said first part is located, andthe bends of at least three arms of the star-shaped grip contact theperiphery of the second part at corners of a triangle within which thecenter of said second part is located.
 15. A rebuilt rechargeablebattery according to claim 8, in which said cells consist of pairs ofcells, and in which both terminals at the ends of the shells of thecells of each pair disposed in said second plane are directly welded toa conductive strip.
 16. A rebuilt rechargeable battery according toclaim 8, in which each of said star-shaped grips has at least five armsuniformly spaced around the hub thereof, and in which each saidconductive connector includes an intermediate part connecting said firstand second parts thereof and overlying at least one arm of each of thestar-shaped grips to which the conductive connector is connected.
 17. Amethod of rebuilding a rechargeable battery comprising a set of spent,electrically interconnected, electrochemical cells of substantiallyuniform size within a battery case, the cells being connected to batteryterminals on said battery case, each of said cells having a cylindricalshell, a positive terminal at one end of the shell, and a negativeterminal at an opposite end of the shell, and said cells being arrangedin an array in which the cylindrical shell of each cell is in closeproximity to the cylindrical shell of at least one other cell in thearray, and in which a first set of ends composed of one end of each ofthe shells is disposed substantially in a first plane and the remainingends of the shells are disposed substantially in a second plane parallelto the first plane and spaced from the first plane by a distancesubstantially equal to the length of each of the shells, the methodcomprising the steps of: removing said set of spent cells from thebattery case; arranging a fresh set of cells in substantially the samearrangement as that of the spent cells, wherein terminals of cells ofthe fresh set at the ends of the shells thereof in said first plane arepermanently connected to metal grips before said fresh set of cells isarranged in said arrangement; establishing electrical interconnectionsin said fresh set of cells corresponding to the electricalinterconnections in said set of spent cells, at least in part byconnecting each of said metal grips to another of said metal grips bymechanically securing first and second parts of a conductive connectorto respective metal grips to be connected; enclosing the fresh set ofcells within said battery case; and electrically connecting said freshset of cells to said battery terminals on said battery case.
 18. Themethod according claim 17, in which terminals of cells of the fresh setat the ends of the shells thereof in said first plane are welded tometal grips before said fresh set of cells is arranged in saidarrangement.
 19. The method according claim 17, in which said metalgrips are star-shaped grips each having a hub and a plurality of armsextending from the hub, and in which the metal grips are mechanicallysecured to said first and second parts of a conductive connector bypositioning the first and second parts respectively in contact with hubsof two star-shaped grips, and bending arms of the grips over said firstand second parts, thereby clamping each of said first and second partsof the conductive connector between arms of a star-shaped grip and a hubthereof.
 20. The method according claim 17, in which terminals of cellsof the fresh set at the ends of the shells thereof in said first planeare welded to metal grips before said fresh set of cells is arranged insaid arrangement.